The present invention relates to a system for measuring depth by measuring the time delay between the transmission of a high frequency sound impulse and the return of the reflected signal.
There are some depth measuring systems such as seen in U.S. Pat. No. 3,942,149, which may have a range portion select feature for a depth display where certain portions of depth range may be selected for finer indication. However, there is a problem with this range portion selector because when the depth is near the border between two range portions, the observer of the display must consciously determine when to change over the select switch to either of the two portions as the depth changes.